I would like to operate a small magnetic SMD buzzer using a coin cell battery. However, magnetic buzzers require at least approx. 40mA to run, which I think is more than a coin cell battery can output. So, is there any possible way to operate a magnetic buzzer using a coin cell battery? Maybe with the use of other components etc? If not, is there an alternative? (I considered a Piezo buzzer but they don't come as small as magnetic buzzers, which are 5mm x 5mm). Thanks.
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\$\begingroup\$ Add a link to the datasheet for the SMD buzzer othewise we're guessing. \$\endgroup\$– TransistorCommented Aug 21, 2017 at 20:58
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\$\begingroup\$ well, you might be able to (slowly) charge a large capacitor with your coin cell and then use that to actuate your buzzer, buuuut: Sounds like a really bad idea. That coin cell is going to be empty, either by plain usage, or by leakage currents of that capacitor in no time. Plus that capacitor is large. In essence: you're using the wrong tools for your job. \$\endgroup\$– Marcus MüllerCommented Aug 21, 2017 at 20:59
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\$\begingroup\$ anyway, @Transistor is right: without knowing the voltages of your coin cell, the behaviour of your buzzer, and the specifics of when, how early, and how long you want to buzz, no chance to do anything but guess. \$\endgroup\$– Marcus MüllerCommented Aug 21, 2017 at 21:00
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1\$\begingroup\$ Hi all, thanks for your answers. The datasheet for the buzzer is here: cui.com/product/resource/cmt-4023s-smt.pdf In terms of the coin cell battery, any will sort of do. Preferably a Zn-Air battery, but I understand they operate at a lower voltage than say the CR2032 \$\endgroup\$– user1390491Commented Aug 22, 2017 at 0:18
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1\$\begingroup\$ @user: Probably nobody saw this information as you buried it in a comment. Add it to your question where it belongs instead. \$\endgroup\$– TransistorCommented Sep 15, 2018 at 21:06
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2 Answers
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You have a fundamental problem in that the coin cell can't put out as much power as the buzzer needs to operate. No amount of conversions or clever circuitry can fix this.
Physics can be inconvenient like that. Either find a way to get more power (bigger battery, more batteries, etc) or a way to require less power (more efficient buzzer, require less sound out, etc).
answered Sep 15, 2018 at 22:37
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if you understood how buzzers and coin cells work for ESR, you would understand your requirements are unrealistic.
A buzzer may have a coil DCR as low as a speaker of 16 ohms, then when it energizes the circuit , contacts will opens with a spring force to return to normally closed like a relay and coil in series. This give the effective average impedance, but not the one needed to start the motion.
The low power source ESR must be much less than the DCR load to minimize voltage drop. Batteries have an ESR somewhat inversely proportional to their mAh capacity and coin cells start in the kilo-ohm range.
You need to make realistic specifications for cost, size, power, energy and ESR with a suitable acoustic performance to realize a decent design.
